Clock shows h hours, m minutes and s seconds after midnight.
Your task is to write a function which returns the time since midnight in milliseconds.
h = 0
m = 1
s = 1
result = 61000
Input constraints:
0 <= h <= 230 <= m <= 590 <= s <= 59
def past(h, m, s)
1000 * (3_600 * h + 60 * m + s)
end